Post by: dtcerrato

For our coach, unless it gets higher than the low to mid-80s, sunscreens on most windows, with three roof vents open, will suffice. Otherwise, the roof air will come on when the generator is on.  Or we'll use the Over-the-Road A/C with the inverter.

Post by: Dave5Cs

I use split-unit A/Cs, an inverter, and lots of batteries.

Post by: luvrbus

Don't let these guys tell you that a 12,000-BTU mini-split with batteries will replace a 64,000-BTU AC unit on a bus.  It doesn't happen in the real world.  I know people with $20,000 worth of lithium batteries, two inverters, three 9,000 BTU mini-splits, and solar panels that fight the heat.  They think they are in heaven at 100+ degrees if they get the temp inside the bus down to 85 degrees.

Post by: epretot

I did a calculation and quickly determined that simply running a 240V mini-split unit would be fine. No way was solar going to cool the bus sufficiently or economically, and it will kill the battery bank very quickly.

I have a 10kW generator to run the air conditioning units.  Also, a transformer is probably more affordable than two inverters.  I realize the 120V systems can work, but they're just taking the edge off. 

Post by: lvmci

I have three low-profile roof ACs: a 15K BTU unit over the driver’s seat, a 13.5K BTU unit over the kitchen, and a 13.5K BTU unit over the bedroom with a heat strip.  No heat pump for me. I live in the desert, with 100°s throughout the summer and 20s and 30°s in the winter.  I also have a Propane heater in the living room/kitchen, and the bedroom has one of the new Chinese Diesel heaters. Everything is powered by shore power or my 13.5kW diesel generator, which is fed from my diesel engine tank.

Post by: luvrbus

All those buses with factory air are 64,000- to 105,000-BTU AC and heat units and are difficult to replace. With add-on units, factory conversions like Marathon almost all have at least 60,000 BTU on the roof.  Three roof tops on the S&S RV usually provide 45,000 BTU.

Post by: Jim Blackwood

I think my MCI DL has a 93K BTU cooling system.

The first step is to park in the shade. Somehow. Even if it's under a suspended tarp. Next is massive air circulation. If there is no breeze, how about rigging a solar chimney?  That shouldn't be that hard to do, and they can generate pretty good airflow if done right.  In dry climates, a swamp cooler is a bonus, and it's also not too hard to rig. In humid climates, park near water and take a dip in the creek. Except in Florida. Gators ya’ know.

Publisher’s Note:  Check out the TurboKool RV swamp cooler. It draws very little power so they can easily be operated off a small battery bank and solar panels.

Post by: CrabbyMilton

On those unusual hot summer days, if push comes to shove, you can always find a roadside motel.

Post by: windtrader

You've heard some quite large numbers, and they may be reasonable for those Busnuts who need A/C on demand and are fully capable in 100-degree-plus temperatures. Before deciding, you need $15k to meet YOUR cooling needs; first establish your use patterns, then determine capacity and other cooling specs.  The same goes for cold weather conditions, heating requirements, and specs.

A few key considerations and factors to include in your calculations are: Where do you travel? How many days do you expect to be in a location where cooling is required? If you live in northern climates and travel in those zones, you probably do not need much capacity. On the other hand, if you spend many days in Arizona, Texas, or the humid south, then you likely need more cooling. 

How much cooling depends on several factors. How insulated your bus is impacts how much cooling is required, and the difference can be substantial. How much of the coach needs cooling at the same time? Cooling different parts of the bus at different times impacts how much energy you need on demand. For example, we keep the front of our bus cool during the day, then switch to the rear if required later in the day and evening. If we needed to cool the entire bus, that requires double the capacity.

If you don’t have shore power or generator AC, what about solar? There are numerous systems in operation using solar and lithium batteries. Mini-splits use less energy than traditional rooftop units. Having a system that powers a single mini-split is quite achievable today, and costs are coming down all the time.

My recommendation is to do more research, especially on solar/lithium systems.  Do the work to calculate your energy needs on a daily and hourly basis that will help derive specs for systems that do what you want and need.

I don't know where you live, but I'm debating whether to sell off my diesel generator and replace it with a smaller portable unit as a backup when extended periods of low solar can't maintain an adequate SOC (state of charge).

Post by: Tedsoldbus

I was surprised at the flurry of answers. My first question was going to be: What do you have? Or are you looking at a bus that has nothing but over-the-road air?

I have a bus with a big generator and two roof air conditioners, but I also have a wife who likes to go from pole to pole at campgrounds, so we don't really need a generator.  If you are solo in your life, I'd think hard about what Don said about where you're going.  Full-time, or a few trips a year?  In summary, what do you have and what does it have now?

Post by: freds

My idea, which I have yet to implement, is to chase 70-degree weather around the country.

Publisher’s Note: For how to stay in 70-degree weather year-round. Click HERE.

Post by: luvrbus

When sitting on the side of the road for two days in the desert heat, waiting on a tow truck, I believe a generator is a wonderful piece of equipment.  Been there, done that in El Paso one year in July.

Post by: windtrader

Anyone who says solar is all they need has not done it in gray conditions for more than a few days. Without shore power, you have to generate power in addition to solar; i.e., a generator.  Cold is fine on batteries, as electricity is only used to run fans.  The Webasto is diesel-powered and puts out plenty of heat. I would not consider going all-electric heat and ditching the Webasto. I am nuts, but not certified as of yet.

Post by: Satelliteguy

The question is “How will I be using the bus?”  I am interested in living in it full-time and traveling when I feel like moving.  I am hoping to go look at a bus very soon that does not have the generator and AC.  I will not always be in that 70-degree weather, so I hope to get ideas on the best and lowest-cost way to add AC to this coach.  

A mini-split AC/heat unit may be an option.   I’m still trying to get as much info as possible. I hate making bad decisions, as it takes so long to recover from them.   

Post by: Dave5Cs

We don't rely solely on solar power; we also have a small charger when the solar panels cannot deliver enough power.  The charger kicks in and finishes the charge back up to 29.6V by nighttime.  Even though we are on the pole, if it gets nice and sunny, I will shut off the shore and engage the 4024 inverter.  This reduces our electric bill. 

Post by: luvrbus

I see a lot of the new trucks have the 400-hour lithium battery banks, and the AC units are DC.   No AC current or solar.  Buses are easier to cool when parked, but not when moving.  Small compact autos have 20+ BTU for cooling.   

Post by: windtrader

It is important to go in with eyes and a checkbook wide open.  Maybe start over and offer your insights on your bus plans and budget. You may want to reconsider starting with a bus that has no generator or AC, as that will be money invested that won't be recovered. We are all here to help, so don't take any comments negatively.  We really want to help you make the most appropriate decision for your situation.

Post by: Satelliteguy

Thanks to everyone for the suggestions and calculations. What I think I am hearing is, “throw about $15,000 worth of generator and AC parts at it would be helpful”.  I love coming to this forum and reading the discussions. You are some smart Bus people!